- at least 1 melanoma lesion that can be accurately and serially measured in at least 2 dimensions and for which the longest diameter is ≥ 10 mm and with perpendicular diameter ≥ 5 mm as measured by contrast-enhanced or spiral computed tomography (CT) scan for visceral or nodal/soft tissue disease. Lymph nodes must measure > 15 mm in their short axis to be considered measurable by CT scan.